1. Field of the Invention
The present invention relates to a system, method and device for interspinous fixation or fusion and, more particularly, to an expandable interspinous fixation device, and a system and method for using such a device.
2. Description of the Related Art
Interspinous fixation, also called spinal fusion, is one of the more commonly performed surgeries for the treatment of chronic, severe lower back pain. For example, interspinous fixation is often used to treat conditions such as degenerative spondylolisthesis, in which one of the vertebrae slips forward or backward relative to the adjacent vertebra or vertebrae. Symptoms of degenerative spondylolisthesis can include severe lower back pain, decreased range of motion of the lower back, and numbness, tingling, or weakness in the legs due to nerve compression.
Currently used methods of treatment for this condition, and others affecting the spine, include vertebral fixation using intervertebral cages implanted with bone graft using supplemental posterior fixation via pedicle screws and rods to provide segmental stability until a biological fusion occurs. However, spine screws in such a method are positioned very close to nerve root and vasculature along the spine. Further, fluoroscopy is required to visualize screw placement within a patient's anatomy, thus exposing the patient to high levels of radiation.
In recent years, a number of interspinous process devices have been used that provide an interspinous fixation that can typically perform as well as the pedicle screw-rod systems, but with less risk of patient injury. Such devices are typically affixed to, for example, the processes of two adjacent vertebrae. However, these devices provide limited opportunity to incorporate an integral graft material to foster bone growth. Additionally, such interspinous process devices having fixed size limits are suitable for only some patients, but are unsuitable for the anatomy of many patients. These two limitations, in part, have played a role in discouraging broad acceptance from surgeons who could otherwise use these devices.
Accordingly, it is desirable to provide an interspinous fixation device that reduces the likelihood of patient injury, offers integrated graft material, and is well-suited to meet the anatomical needs of practically any patient.